A wide variety of foldable, rectractable, collapsible and pivotable guard rails, side rails, hand rails and similar barriers have been proposed for a variety of uses, each use having different considerations and requirements.
The present guard rail assemblies are particularly designed for use on medical examination tables, such as X-ray tables where unobstructed access to the table top and to the X-ray film cassette compartment beneath the table is essential, and where a guard rail is also essential to prevent a patient from falling from the table top during voluntary movement from one examination position to another or during any involuntary movement which may accompany an injury, such as due to delerium or due to regaining consciousness, etc.
Reference is made to U.S. Pat. Nos. 3,997,792 and 4,084,277 which relate to collapsible guard rail assemblies for X-ray tables. The rail assemblies of said Patents are in current use but have certain disadvantages. Firstly, they are difficult to move from raised position to lowered position because the two retaining means which lock the assembly in raised position, i.e., the locking sleeves must be individually manually raised above the mounting means before the assembly can be pivoted to lowered position. This requires the use of both hands whereas single hand operation is desirable to leave the other hand free to stabilize the patient. Also the hands can be injured if they are caught between the assembly and the edge of the table as the assembly is moved to lowered position.
Another disadvantage arises from the use of the retainer sleeves and springs which require assembly and which can wear and break as a result of the frictional contact between the sleeves and the upright supports and the compression of the springs during repeated use.
Another disadvantage arises from the spaced mounting members which must be precisely spaced when attached to the side of the table, or else the assembly will not move properly between raised and lowered position.
A variety of different locking means have been proposed for guard rails of all types but such always require the use of two hands, i.e., one hand to release the lock and the other hand to pivot the guard rail to lowered position. Reference is made to U.S. Pat. Nos. 3,840,917 and 3,930,273 which employ a locking lever, and U.S. Pat. Nos. 2,972,153 which broadly teaches a number of locking means. In each of these cases there is no suggestion of a locking means which enables the operator to unlock the raised assembly and move it to lowered position with one hand in a single operation, and the locking means disclosed involve additional moving parts which add to the expense of the assembly and which represent projections which obstruct the free access to the underside of the table and/or detract from the simple appearance of the assembly, particularly when the assembly is in lowered, folded position.